Reversible Isomerization and Cure Monitoring of Epoxy Azobenzene Resins

The photoresponsive behavior of the glycidyloxyazobenzene (GOAB) monomer, synthesized using an improved method, is examined by UV/Vis spectroscopy. The monomer is cured with diethylenetriamine (DETA), forming a new epoxy resin. Proton NMR spectroscopy is used to monitor the completion of the curing reactions. Kinetics for reversible trans and cis isomerization in the cured system and also in the epoxy monomer are identified by UV/Vis spectroscopy during in situ irradiation with appropriate wavelengths (290-320 nm for UV and 400-500 nm for visible). The rates of recovery of the monomer from cis to trans forms are also obtained by heating and storing in the dark. Furthermore, the reactivity of the monofunctional GOAB monomer with a common amine, DETA, as a curing agent, is investigated using isothermal and dynamic heating scans in a DSC pan and by simultaneously monitoring the near-FTIR spectra. The modified epoxy azobenzene proved to be reactive enough with DETA to form a network that can sustain temperatures of up to 200 degrees C. (C) 2014 Wiley Periodicals, Inc.